Apple released Mac OS X 10.6.4 update which is recommended for all users of iMac (Mid 2010). This latest Mac OS X update includes fixes from the Mac OS X 10.6.4, and also includes some new specific fixes for iMac (Mid 2010):

• Resolves compatibility and performance-related graphics issues
• Improves compatibility with large-format SDXC memory cards
• Adds support for Magic Trackpad

Download Mac OS X v10.6.4 for iMac (2010)